I just recently started to talk to a therapist a couple of weeks ago. I have an appointment this coming Thursday, so I think it's probably a good topic I bring up. I can't say that I love having the topic always revisited. There will be months where I don't even think about it much. Then we'll have some conversation, or I'll run into him, and he'll reminisce about something, and even then, sometimes it's alright. This time around, it was just him telling me he'd met someone else. It just spawned this whole thing in my head.
I'm not against thinking that perhaps he just lost feelings for me, but I guess it just didn't seem to make sense. Two weeks prior to it all, he was telling his parents all about me. Showing them photos of our trip. We hadn't fought, or had a bad time. I just think there was a lot of pressure on him to keep with this "I'll seek help by X date," and he just wasn't ready for it. I'm not saying we didn't have issues, and there's definitely issues I should resolve in myself, too. I ask myself a lot of times, why did I even stay? The second he told me he had trouble with booze, why didn't I say, "Hey. I really like you. A lot. But you should probably seek help, and when you've done that and get all squared away, look me up." Instead, I (like you said) romanticized it and thought, "Ooo, maybe I could be the reason he gets help, and we'll make it through this hard time, and come out on the other side to lillies and tulips and kitties and sunbeams! Yay!" Didn't quite work that way.
I've made myself invisible to him on instant messenger, so he can't see when I'm online. Since he never calls me, or reaches out except when he's horny or bored, I figure that covers that whole spectrum.